Abstract:

Initial results from a successful laser-controlled
collective ion acceleration experiment at the
University of Maryland are presented. In the
experiment, positive ions are trapped in the potential
well at the head of an intense relativistic electron
beam injected at current levels above the space charge
limit. Seed ions for acceleration are provided by puff
valve injection of a neutral gas cloud localized to
within 3 cm of the injection point. Control over the
acceleration of the well and the ions is then achieved
by means of a laser-generated ionization channel
produced by passing the light from a O-switched ruby
laser though a series of partially and fully reflecting
mirrors in such a way as to provide time-sequenced
laser ionization of a target located on the drift tube
wall. Using this system, controlled acceleration of
protons at a rate of approximately 40 MV/m has been
demonstrated over a distance of about 50 cm.